Conventionally, an apparatus that causes a plurality of liquid materials or a powder material in a slurry to pass through a narrow gap between a rapidly rotating rotor and a stator that does not rotate such that those materials are continuously dispersed by a strong shearing force caused by the rapid rotation has been known (for example, Patent document 1). Incidentally, the term “dispersing” shall mean uniformly dispersing a powder material in a slurry, or uniformly mixing a plurality of liquids. The disperser disclosed in Patent document 1, etc., has flat opposing surfaces where the rotor and the stator face each other such that dispersing is carried out by a shearing force generated between the surfaces.
However, the disperser has a problem in that a raw material discharged from the disperser must be reapplied to the disperser by means of a pump, etc., to circularly disperse it, or two or more of the dispersers must be connected in series to carry out two or more dispersing steps, if a desired dispersive state cannot be achieved in one pass, because the raw material quickly passes through the gap between the rotor and the stator.
Also, the disperser has a problem in that dispersing cannot be carried out efficiently and appropriately, because small grains that do not need to be dispersed receive excessive shearing energy, if the time for dispersion is set at a time sufficient to cause the coarse grains (aggregated bodies) that need to be dispersed to disappear. Incidentally, herein a small grainy material formed by solid particles (powder materials) and an aggregate consisting of an aggregated body of them shall both be referred to as “the grains.”    Patent document 1: JP2000-153167